Bed covering designs and arrangements in common use have remained largely unchanged for many years, and generally involve the use of a bottom sheet to cover the mattress, a top sheet to cover a sleeper lying on the bottom sheet, and additional blankets or coverings placed above the top sheet when needed or desired. Fitted bottom sheets, with a pocket at each corner to fit around and under the mattress, have been known for some time and have become the conventional design because they are easily installed and removed, and because they stay in place much more reliably than flat sheets. In the conventional approach, however, separate flat top sheet have continued to be the norm, despite disadvantages and problems with their use. Those disadvantages and problems include difficulty in properly aligning the top sheet on the mattress; difficulty in tucking the ends and edges of the top sheet under the mattress, especially when the bed is placed with one side against a wall or access to one side is otherwise obstructed; and difficulty in maintaining the position and attachment of the top sheet during use.
Particular problems exist with bed designs in which one side of the mattress is obstructed, such as with bunk beds which often include a rail on one side to help prevent a sleeper from falling out of the bunk. Beds are also often placed with one side directly against a wall to, for example, maximize floor space in children's rooms, dormitory rooms, apartment bedrooms, cabins, and the like. In those instances access to the obstructed side can be gained only by moving the bed, if possible, by climbing onto the bed, or by reaching over the bed from the unobstructed side.